Vibrating and other separatory screen assemblies are generally known in the art and are very useful in accomplishing the separation of materials on the basis of size of the materials to be separated. A slurry of liquid and entrained solids will be caused to run or flow across an upper surface of a screen panel assembly. Particles of a certain size and above will not pass through apertures in the screen panels and will thus be separated out. The screen panel assembly is caused to vibrate by an suitable means with this vibratory motion being beneficial in facilitating the proper separation of the material directed to the screen panel.
One such vibratory screen panel assembly is shown in U.S. Pat. Nos. 5,112,475 and 5,277,319, both the Henry, and both assigned to Conn-Weld Industries, the assignee of the present application. In these two patents, there is disclosed a panel mounting system for a vibrating screen assembly, and a panel which is securable in the vibrating screen assembly using the panel mounting system. A plurality of screen panels are secured to a panel deck of a frame portion of a vibrating screen assembly. A plurality of elongated hold downs or center retainers, which are made of a resilient elastomeric material, such as polyurethane, are provided with spaced anchoring pins along their bottom surface. These anchoring pins are receivable in apertures in an anchor member. Once the hold down members or center retainers have been secured to the anchor member, which is, in turn, attached to spaced cross members or tubes of the frame of the vibratory separator, the screen panels are placed atop the panel deck with their side edges in contact with the center retainers. Elongated key members are inserted into upwardly facing slots in the center retainers to spread wing portions of the retainers laterally outwardly. This spreading of the wings of the center retainers causes the wings to grip the side edges of the screen panels so that these panels are secured in the vibrating screen assembly.
The panel mounting system disclosed in the two above-referenced Henry patents, which are assigned to Conn-Weld Industries, utilizes screen panels and cooperating anchor members which are bolted, welded or otherwise secured to cross members of the panel deck of the vibrating screen assembly. An owner of a vibrating screen apparatus which is not provided with the appropriate anchor members disclosed in the prior Henry patents must make substantial revisions and modifications to his vibrating screen assembly if he is to be able to enjoy the advantages of the Conn-Weld Industries panel mounting system.
A center retainer assembly for a panel mounting system is disclosed in U.S. Pat. No. 5,398,817 to Connolly et al. and also assigned to Conn-Weld Industries. The center retainer assembly described in the '817 patent utilizes an elongated bolting bar which is encased in a resilient material and which includes an elongated center retainer. The center retainer assembly is placed into an upwardly facing retainer channel and is secured to the retainer channel by placement of the bolts carried by the bolting bar through holes in the retainer channel. The retainer channel is, in turn, secured to mounting plates that are attached to a cross tube or to a cross bar of a vibrating screen assembly.
Each of the screen panel retainer systems described in the above-mentioned patents has performed well and has been accepted by the industry. However, each still has required that the industry standard configuration of screen stringer rails placed atop cross tubes or cross bars of the frame portion of a vibrating separatory machine be modified in some way. Such modifications or re-fittings inevitably take time, require the services of technicians and meet with resistance on the part of equipment owners who want to purchase screen panels and panel retainers that will fit the machinery they already have, without the need for any modification, revision, re-working or equipment downtime.
Thus the need still exists for a screen panel retainer system that is compatible with current industry standard screening machines. In addition, the screen panel retainer system must have the capability to accommodate to both new machines, as well as to older, used machines. The screen stringer rails which are secured atop the cross tubes or cross bars of the typical vibrating separatory machine, are typically configured with spaced holes along their upper faces. These spaced holes are used for the attachment of the screen panels to the machine's frame.
When the machine is new, all of the holes on the screen stringer rails are of uniform size. A number of currently available screen panel retention systems depend on the proper dimensioning of those holes to accomplish the securement of the screen panels to the machine frame.
Vibrating separatory machines are frequently used in applications in which a relatively abrasive material is separated from a suspension fluid, such as water. The slurry of fine abrasive particles and the suspension fluid finds its way into all of the components of the screen assembly, including into the spaces that exist between the screen panel connection mechanisms and the holes or apertures in the screen stringer rails. Over the course of time, the slurry abrades the holes and causes them to enlarge. This abrading action is enhanced by the vibration to which the separtory machine is continually subjected.
Eventually, these holes in the screen stringer bars become enlarged. Since a number of the currently available panel retainer systems utilize some type of an interference fit of pins, pegs or the like into these holes, their enlargement is problematic. At some point, the stringer bar holes become so enlarged that they will no longer engage the pins or pegs with sufficient retentive force. At such time, the stringer bars have to be refurbished, the screen panel retainers have to be modified or the stringer bars simply have to replaced with new bars. In each instance, the process involves considerable work and the equipment being taken out of service.
A need thus exists for a screen panel retainer system which is suitable for use with stringer bars whose mounting holes are both properly sized and also ones that have become oversized due to wear. The screen panel retainer system of the present invention provides a device and an assembly which can accommodate a much greater variance in screen stringer rails than has been possible in prior systems. the screen panel retainer system of the present invention is a substantial improvement over the presently available systems.